Ecumenopolis (from Greek: οἰκουμένηoecumene, meaning "world", and πόλιςpolis "city", thus "a city made of the whole world"; pl. ecumenopolises or ecumenopoleis) is the hypothetical concept of a planetwide city. The word was invented in 1967 by the Greek city planner Constantinos Doxiadis to represent the idea that in the future urban areas and megalopolises would eventually fuse and there would be a single continuous worldwide city as a progression from the current urbanization, population growth, transport and human networks.[1] This concept was already current in science fiction in 1942, with Trantor in the Foundation series.[2] When made public, Doxiadis' idea of ecumenopolis seemed "close to science fiction", but today is "suprisingly pertinent" according to geography researchers Pavle Stamenovic, Dunja Predic & Davor Eres[1], especially as a consequence of globalisation and Europeanisation.

Before the term had been created, the concept had been previously discussed. The American religious leader Thomas Lake Harris (1823–1906) mentioned city-planets in his verses, and science fiction author Isaac Asimov used the city-planet Trantor as the setting of some of his novels. In science fiction, the ecumenopolis has become a frequent topic and most recently popularized by the planet Coruscant in the Star Wars universe.